The Canal Turn at Aintree Racecourse, with EasyFix frames and plastic birch installed, before being dressed with spruce.

British racing authorities have outlined the safety measures in place on the Aintree course ahead of this weekend’s Grand National steeplechase, while acknowledging there remains a risk of injury.

The gruelling race attracts global attention, but the event has been criticised by some animal rights advocates, who say too many horses die on the challenging course.

The race has claimed 11 horses since 2002, but no fatalities were recorded in last year’s running of the race.

The British Horseracing Authority said the welfare of the sport’s equine and human participants was paramount, pointing out that £1.5 million had been invested in safety and welfare measures at the course since 2009.

Replacing the previous timber central frame, or core, of all fences with more forgiving plastic birch and natural birch. This followed a research programme instigated by Aintree and the authority in 2011. The dimensions of all fences remain unchanged, as does their appearance.

Moving the start 90 yards forward away from the stands, the objective being to create a calmer and more controlled environment at the start for both horse and rider.

Further investment in the racing surface, with £400,000 spent on enhancing Aintree’s watering system to ensure the safest possible jumping ground possible.

Levelling the landing side of some fences, including at the notorious Becher’s Brook jump.

The authority said the modifications built on measures introduced after a major 2011 review, which, among other things, led to stricter qualification criteria for horses and jockeys and an air-cooled wash-down area for horses after the race.

Maintaining the current height and dimensions of the fences was considered important in order to deter increased speed, it said.

“The evidence shows that races over the Grand National course are becoming safer, reflecting the measures that have been implemented to raise welfare standards,” the authority said.

“In races run over the Grand National course, including the Grand National itself, the average injury and fatality rate over the last 10 years has decreased compared to that over the last 20 years.”

However, the authority acknowledged the risks.

“Despite the best efforts of all involved, as with participation in any sport involving speed and athleticism, there remains an inherent risk of injury.

“British Racing is open and transparent about the risks involved in the sport,” it said, noting that the equine fatality rate has fallen by one third to 0.2 percent of all runners over the last 15 years.

“However, despite all the measures taken horses remain at risk of serious injury throughout their lives, regardless of the type of equestrian activity they participate in, even when turned out in a field, exercising at home or doing what they were bred to do, namely racing on the track.”

The British-based animal rights group, Animal Aid, which has been vocal in its criticism of the risks in the Grand National and in racing in general, voiced its concern over the death rate in the nation’s racing.

It said at least 22 horses died on British racetracks in March.

“The overall equine death rate for March is more than four times higher than for the same month last year, when five horses died.”

It said around three horses had died each month since it began recording on-course deaths in March 2007.

It demanded that the British Racing Authority publish on an ongoing basis the on-course death toll in plain fashion, including the number of horses, their names, where the deaths occurred and the injuries sustained.

The group’s horse racing consultant, Dene Stansall, said: “The Grand National has high risk designed into it, making the race an efficient killer of horses.

“But, as we approach the noisily hyped 2014 event, we need also to consider the many silent equine victims being killed at racecourses around the country.

“Animal Aid is calling on the British Horseracing Authority finally to dispense with its complacency, drop the excuses and admit that there is a major horse welfare problem – one that, as an apologist for the racing industry, it is incapable of addressing.”